Stomach data

[lentinj]

lentinj:

On a different note, Predator / Prey relationships. The greatest level of detail I can find (OutputNoFishDietCheck.txt) is consumption per second (I think?) by predator species, predator ageClass & prey species.

cddesja:

That is probably your best bet and yes that is suppose to be number of individuals consumed per individual or, in the case of a biomass pool (e.g. an invert), mg N consumed per second. There are some other files that you might take a look at that look at specific predator induced mortality. But I haven't figured out what the units are and the numbers look very strange.

lentinj:

individuals consumed / sec will need a fair bit of interpretation anyway. Can we assume that any species ingests at a fixed rate (this doesn't seem something that Atlantis will tell us), so e.g. a cod's stomach content for one month can be (consumption/sec) * ingestion time. We could go further and break it up into digestion stages I guess.

[lentinj]

Master now has a version of this, I'm not convinced of it's usefulness but is probably going in the right direction.

[erlasturl]

DietCheck.txt does not contain consumption per second it tells the diet in proportions so no information here on how much the predators are consuming.

[lentinj]

@erlasturl No information in DietCheck, or no information at all? There's various other Predator Mortality tables that sound promising, but Chris wasn't sure of the units, as above.

[erlasturl]

There is information in the DietCheck on what the predators are eating in proportions just not how much they are eating of each prey. For example for the predator cod may have 0.3 for the prey capelin, that means that the cod diet consist of 30% capelin.

I don't know what the predator mortality is but there is also a variable called Eat in the PROD.nc file that may be useful for calculations on consumption, that is how much the predators are eating. I think Beth has rewritten that output so now it is suppose to show what is says it is showing which I think was consumption in mg N per day. But I haven't verified it.

[lentinj]

Okay, in the output I've got (which could easily be out of date) has things like Cod1_Eat(t, b), so mgN by time/box. But does this represent consumption:

• ...per second or over this time period?
• ...per individual or for the whole functional group / cohort?

Regardless, combine that with DietCheck and mgN conversion and you can get total weights of each species. That's sounding useful.

[erlasturl]

The output shows the consumption rate at time t in box b. This is in mg N per m3 per day for that cohort. So will also need the density for that cohort to calculate consumption per individual which you get from the Out.nc file where you have the numbers and the volume of the boxes. And yes, by combining the info from the DietCheck with this one you get consumption by prey.

[lentinj]

Yeah, I'm already reading Out.nc so that part isn't a problem.